This document provides strategies for eliminating irrigation overspray and runoff in landscaping. It discusses converting spray systems to drip irrigation, using permeable groundcovers, and installing buffers. For runoff, it recommends adjusting application rates and amounts using techniques like aerating soil or installing weather-sensitive controllers. Resources for different irrigation products and controllers are also listed.

1. Office of Sustainability and the Environment
Watershed Management Section
200 Santa Monica Pier, Suite C
Santa Monica, CA 90401
russell.ackerman@smgov.net
(310) 458-8972 ext 2
Strategies for Eliminating Irrigation Overspray and Runoff
Santa Monica Municipal Code 7.16.020 and 8.108 Subpart B prohibit irrigation
overspray and/or runoff onto hardscapes such as gutters, streets or alleys.
Any changes to your irrigation system must be in compliance with the Green
Building Ordinance – visit www.sustainablesm.org/landscape for more info
Overspray -- Spray irrigation devices require frequent maintenance and
adjustment to keep their spray directed where you want it.
Here are five strategies for mitigating or eliminating overspray:
1. If your landscape is composed of individual plants, such as shrubs, rather
than continuous groundcover like turf; convert your spray system to drip
irrigation.
2. Relandscape with individual plants (one-gallon size or larger). You must
convert the spray system to drip irrigation (with emitters 2 gph or less).
3. Replace the plant material with a permeable, non-living groundcover such
as decomposed granite that will not require irrigation.
4. Install a buffer strip of permeable, non-living groundcover such as
decomposed granite between the plant material and the hardscape. You must
move the sprinkler heads inward 24 inches to the edge of the planting bed.
(See drawing below) Because of the possibility of wind and misadjustment,
this solution is not fool-proof.
. = sprinkler
24“
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2. 5. Install a non-spray irrigation system such as ECS, SurfaceFlow, KISSS or
subsurface drip. See RESOURCES below. Note that these systems may be
relatively costly.
Runoff results from overspray onto hardscape, application of water faster
than the soil can absorb it and/or application of more water than the soil can
hold.
Here are some strategies for eliminating runoff:
1. If the application rate is too fast –
A. Adjust your irrigation controller to apply the water in several short
cycles with a soak-in period between cycles. This is especially
important if the planting area is sloped.
B. If your landscape is several years old, have the soil aerated.
C. If your landscape is turf, have it dethatched. Your gardener should
be able to do this.
D. If your irrigation system is composed of sprayheads (fixed spray
patterns of quarter, half and full circles) with eight-foot or greater
radius, change to rotor-type nozzles. See RESOURCES below.
2. If you are applying too much –
A. Adjust your irrigation controller. Use the Watering Calculator at
http://www.bewaterwise.com for guidance.
B. Install a weather-sensitive irrigation controller that will automatically
adjust itself for weather changes. See RESOURCES below.
RESOURCES
Rotor-Type Nozzles
MP Rotator http://mprotator.com
Rain Bird http://www.rainbird.com
Non-Spray Watering Systems
SurfaceFlow http://jardinier-asis.com/turf.html
ECS http://www.ecsgreen.com
KISSS http://www.kisssusa.com/
Subsurface Drip Products
Geo-Flow http://www.geoflow.com/landscape.html
Netafim http://www.netafim-usa-landscape.com/Landscape/
Explanation of Aeration
http://ag.arizona.edu/pubs/garden/mg/lawns/aeration.html
Explanation of Dethatching
http://ag.arizona.edu/pubs/garden/mg/lawns/dethatching.html
Examples of equipment for converting sprinklers to drip -
http://www.rainbird.com/drip/products/control/retrofit_kit.htm
Examples of weather-based controllers –
http://www.irrigation.org/SWAT/Industry/ia-tested.asp